Same here.I wasn't aware of the conditional probability when I was doing it so bascially I did the numerator part only.
Your solution is just too perfect !! I totally get it now. Thanks
but is there a technique to look out whether it is a conditional probability or not?
That one was one of the more difficult ones to realise that it was conditional.
'Daniel receives telephone calls on both Monday and Tuesday' was the statement which tells us it was conditional.
Generally anything that isn't directly asking you to find the probability of it will often be key in some other way, in this case as a condition. Other things to watch out for are 'given that', 'if', and 'when,' although above shows that these aren't always used.